1. Fields and Isolines

2. WHAT IS A FIELD?
A FIELD IS A REGION OF SPACE THAT HAS A MEASURABLE QUANTITY AT EVERY POINT
A FIELD MAP IS USED TO REPRESENT ANY QUANTITY THAT VARIES IN A REGION OF SPACE

3. EXAMPLES
FIELD MAPS
TEMPERATURE
PRESSURE
PRECIPITATION

4. ISOLINES LINES ON A MAP THAT CONNECT POINTS OF EQUAL VALUE
ISOTHERMS – LINES OF EQUAL TEMPERATURE
ISOBARS – LINES OF EQUAL PRESSURE
CONTOUR LINES – LINES OF EQUAL ELEVATION

5. **ENERGY ALWAYS FLOWS FROM AN ENERGY SOURCE TO AN ENERGY SINK**
ENERGY SOURCE – REGION OF THE HIGHEST ENERGY VALUE IN A FIELD
ENERGY SINK – REGION OF THE LOWEST ENERGY VALUE IN A FIELD
**ENERGY ALWAYS FLOWS FROM AN ENERGY SOURCE TO AN ENERGY SINK**
DYNAMIC FIELD - A FIELD WHICH CAN CHANGE
STATIC FIELD - A FIELD WHICH REMAINS THE SAME

6. HOW TO DRAW ISOLINES 1.) ISOLINES CONNECT POINTS OF EQUAL VALUE
2.) VALUES OF ONE SIDE OF AN ISOLINE ARE LOWER, WHILE ALL VALUES TO THE OTHER SIDE ARE HIGHER.
3.) ISOLINES NEVER CROSS ONE ANOTHER
4.) ISOLINES MAY FORM CLOSED LOOPS

7. HOW TO DRAW ISOLINES CONT’D
5.) ISOLINES NEVER END SO THEY SHOULD BE DRAWN TO THE EDGE OF THE MAP, UNLESS THEY FORM A LOOP
6.) ISOLINES TEND TO PARALLEL ONE ANOTHER
7.) ISOLINES ARE CURVED AND/OR SMOOTH WITH NO SHARP TURNS OR CORNERS.

8. HOW TO DRAW ISOLINES CONT’D
8.) ISOLINES ARE DRAWN ACCORDING TO A DESIGNATED ISOLINE INTERVAL. (ON A TOPOGRAPHIC MAP, THIS IS CALLED THE CONTOUR INTERVAL)
9.) ISOLINES SHOULD ALWAYS BE DRAWN IN PENCIL FIRST, TO ALLOW FOR REVISIONS

9. GRADIENT CHANGE IN FIELD VALUE GRADIENT = CHANGE IN DISTANCE
THE RATE AT WHICH A FIELD VALUE CHANGES OVER DISTANCE
CHANGE IN FIELD VALUE
GRADIENT =
CHANGE IN DISTANCE

10. DRAWING ISOLINES
CLASSROOM TEMPERATURES RECORDED IN CLASS DURING THE WINTER
THE TEMPERATURE INTERVAL FOR THIS MAP IS 2ºF
LET’S DRAW THE LINES!
FRONT

11. YOUR LINES SHOULD RESEMBLE THE LINES IN THE DIAGRAM BELOW!

12. TO CALCULATE THE GRADIENT BETWEEN POINTS A AND B
1.) FIND THE TEMP. DIFFERENCE BETWEEN THE TWO POINTS
2.) MEASURE THE DISTANCE BY MARKING THE END POINTS ON A PIECE OF PAPER AND THEN COMPARING TO THE SCALE.

13. PLUG THOSE NUMBERS INTO THE FORMULA
GRADIENT= CHANGE IN FIELD VALUE
CHANGE IN DISTANCE
GRADIENT = 12ºF
16 FT
GRADIENT =

14. NOW LABEL THE ENERGY SOURCE AND THE ENERGY SINK FOR THIS FIELD
IS THIS A STATIC OR DYNAMIC FIELD?

15. FOR MORE PRACTICE ON-LINE GO TO THE LINKS ON MY WEB-SITE